The medieval Silk Road brought a wealth of products, spices and ideas from China and Central Asia Europe. In 1346, trade probably also carried the deadly bubonic plague that killed almost half of all Europeans within 7 years, in what is known as the Black Death. Subsequent outbreaks in Europe are thought to have arrived on the east by a similar path. Now, scientists have evidence that a virulent strain of the bacterium Black Death lurked for centuries in Europe while working his way back to Asia, with terrifying consequences.
At the Society for American Archaeology meetings earlier this month in Orlando, Florida, the researchers reported the analysis of the remains of medieval victims in London; Barcelona, Spain; and Bolgar, a town along the Volga River in Russia. They determined that the victims all died a very similar strain of Yersinia pestis , the plague bacteria, which has mutated in Europe, then traveled to the east, in the following decade black death. The results "are like beads on a string" which begins in Western Europe, said Johannes Krause of the Max Planck Institute for the Science of human history in Jena, Germany, author of a soon-to-be study -published. (The lead author is Maria Spyrou, also in Jena.)
This string can be stretched far beyond Russia. Krause argued that a descendant of the 14th plague bacteria of the century has been the source of most of the major epidemics in the world, including those that raged through East Asia in the 19th and 20th centuries and a distressing Madagascar today. Eric Klingelhofer, a distinguished archaeologist at Mercer University in Macon, Georgia, called the presentation of Krause "a good piece of research." But molecular microbiologist Holger Scholz in Munich, Bundeswehr Institute of Microbiology in Germany is skeptical. "I think it is unlikely that China strain came to Europe, he has survived for hundreds of years, and returned to China," she said. "That sounds pretty adventurous."
Advances in DNA sequencing pathogens found in ancient human skeletons are causing new research and debate on the spread of the plague. Thank you to a series of recent discoveries, the idea that the plague remained in Europe for centuries after the Black Death, rather than coming in repeated waves of Asia as long assumed historians, is gaining ground.
A team led by Lisa Seifert at Munich Ludwig Maximilian University reported in January that the Black Death strain persisted in Europe for at least three centuries, based on DNA sequences from eight skeletons of two landfills in Germany that lasted from the 14th to 17th centuries. The sequences were "very similar" to those of previous European victims, according to the study, which included Scholz. While not excluding the continuous waves of plague from Asia, the team concluded that there was "a long persistence of the pathogen in a tank yet unidentified" -perhaps rats.
Also in January, a team led by Kirsten Bos in Jena Max Planck Institute reported further evidence that the descendant of the Black Death strain hooked in Europe, involving the last major European outbreak of plague in Marseilles , France. using the DNA of the teeth of five people who died in 1722, the group concluded that the Y . pestis strain Marseille probably evolved from the plague black. "Our results suggest that the disease was hiding somewhere in Europe for several hundred years," said Bos, whose team included Krause.
Now Krause drew the eastward spread of the Black Death. His team studied the skeletons from a cemetery near the Tower of London firmly dated to 1348-1350, in the wake of the Black Death, as well as a cemetery Barcelona radiocarbon dated mid 14th century. Russian evidence comes from a site that included parts in 1360; burial is estimated to have occurred between the beginning of 1360 years and sequencing of 1400. DNA from three locations showed the same strain of Y . pestis . This strain appears to be the ancestor of the one that killed millions in the 19th century, China, based on the phylogenetic indices.
"If the plague in China was actually of European origin, it is a cruel irony of history," said Klingelhofer, who notes that this was the time when the Western powers dominated China . Krause adds that plague affecting Madagascar as recently as last year also appears genetically related to the variety that spread to eastern Europe in the 14th century.
The researchers are keen to create a family tree of the plague in order to understand the movements and the impact of different varieties of Y . pestis through time and space. Krause argued that three of the four branches of plague appear to have evolved in Asia. But he says the industry related to the strain that developed in Europe immediately after the Black Death proved the most mobile and devastating.
Krause admits that between the 14th century and 21st century London Madagascar, there are "many missing steps" to identify the precise movements of the deadly bacteria. But he said understanding long journey from the plague could help researchers limit its further spread.
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